This invention relates to a fluidic oscillator, especially a liquid oscillator, which is one-piece moldable and of the type disclosed in the above applications, and in which the sweep angle is enlarged simultaneously with improvement in the periodicity of oscillations.
There are a large number of fluidic oscillators useful for issuing a sweeping fluid stream into ambient. See, for example, Stouffer U.S. Pat. Nos. 4,652,002, 4,508,267, Bray U.S. Pat. Nos. 4,463,904, 4,645,126, Turner U.S. Pat. No. 3,432,102, Walker U.S. Pat. No. 3,507,275, Viets U.S. Pat. No. 3,998,386, Stouffer et al. U.S. Pat. No. RE 33,158, Bauer U.S. Pat. No. 4,157,167, Stouffer U.S. Pat. No. 4,151,155, and Bauer U.S. Pat. No. 4,184,636 are free of feedback channels: Stouffer '155 depends on vortices alternately shed from an island and Bauer '636 uses a reversing chamber feeding a separate output chamber. While Stouffer '155 can be molded in a single molding so that it does not require assembly, its frequency of oscillation is high. In a previous oscillating device called a "Travetron", alternating vortices were formed but these were high pressure devices and the vortices cavitated and the oscillation chamber was wider than it was long. U.S. Pat. No. 4,721,251 discloses a fluidic oscillator having walls defining first and second chambers with the second chamber being stepwise widened from the first chamber and having a "turn" wall for turning the branch flow therein to collide with a deflected main jet to push the main jet in an opposite direction. The laterally spaced sidewalls of the first chamber serve as sucking and deflecting walls. The second chamber and its laterally displaced sidewalls make the unit wider than its length.
In our above-referenced U.S. patent application Ser. No. 07/759,557, the oscillator functions with a slight aperiodicity and noise. Our U.S. patent application Ser. No. 07/771,979 provided an improved fluidic oscillating nozzle for dispersal or distribution of fluid in which oscillation is enhanced relative to the periodicity and noise reduction of the oscillation, and more particularly, to a feedback passage-free oscillator having stabilizer means and which operates at low pressure and which can be made at lower cost, preferably in a single molding and does not require expensive assembly equipment and which eliminates problems from sealing. The unit is simpler than prior art designs and has a good fan angle.
According to our U.S. patent application Ser. No. 07/771,979, a low pressure, feedback passage-free fluidic oscillating nozzle has an oscillation chamber having a length L which is greater than its width W, with top and bottom walls, a pair of mutually facing sidewalls, an upstream wall and a downstream wall. An input power nozzle is formed in the upstream wall and has a width PW and a depth D and issues fluid into the oscillation chamber. The downstream wall or side of the oscillation chamber has an outlet formed therein such that pressure within the chamber is always positive relative to ambient. A pair of short walls diverge from the outlet opening in a downstream direction. A feature of that invention is that a pair of alternating pulsating, cavitation-free controlling vortices are formed in the chamber on each side of the fluid stream flowing through the chamber and centers thereof are translated as they grow and stabilizer rib means in the top and/or bottom walls aid the controlling vortices at their downstream supply from the jet and retard them at their upstream end to impart a net increase in strength to the controlling vortices.